The E3 ubiquitin ligase CHIP selectively regulates mutant epidermal growth factor receptor by ubiquitination and degradation
The E3 ubiquitin ligase CHIP selectively regulates mutant epidermal growth factor receptor by ubiquitination and degradation
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DOI：
10.1016/j.bbrc.2016.07.111
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发表时间：
2016-10-14
影响因子：
3.1
通讯作者：
Lee, Jeong Eun
中科院分区：
文献类型：
--
作者：
Chung, Chaeuk;Yoo, Geon;Lee, Jeong Eun
表皮生长因子受体(EGFR)酪氨酸激酶结构域的体细胞突变是肺腺癌对EGFR酪氨酸激酶抑制剂(EGFR-TKIs)治疗反应的决定性因素。突变的EGFR的稳定性由多种调节因子维持，其中包括热休克蛋白90(Hsp90)。Hsc70相互作用蛋白(CHIP)的C末端是Hsp70/Hsp90共伴侣，具有E3泛素连接酶活性。高亲和力的Hsp90-芯片复合体识别并选择性地调节它们的客户蛋白。CHIP还独立于Hsp70/Hsp90发挥其自身的E3连接酶活性。在此，我们研究了CHIP在肺腺癌中调节EGFR的作用，并评价了CHIP对突变型EGFR作用的特异性。在转导WT EGFR或EGFR突变体的HEK 293T细胞中，CHIP的过表达选择性地降低了某些EGFR突变体(G719S、L747_E749del A750P和L858R)的表达，但不影响WT EGFR的表达。在下拉实验中，CHIP选择性地与EGFR突变体相互作用，同时诱导它们的泛素化和蛋白酶体降解。CHIP可下调突变型EGFR在PC9和H1975中的表达，而对WT EGFR在A549中的表达几乎没有影响。此外，CHIP过表达抑制了EGFR突变细胞系的细胞增殖和移植瘤的生长，但不抑制WTEGFR细胞系的生长。芯片对EGFR突变体的特异性泛素化可能为肺腺癌中EGFR的调控提供了重要的机制。我们的结果表明，芯片可以成为克服EGFR TKI耐药的新的治疗靶点。(C)2016 Elsevier Inc.保留所有权利。
Somatic mutation in the tyrosine kinase domain of epidermal growth factor receptor (EGFR) is a decisive factor for the therapeutic response to EGFR tyrosine kinase inhibitors (EGFR-TKIs) in lung adenocarcinoma. The stability of mutant EGFR is maintained by various regulators, including heat shock protein 90 (Hsp90). The C terminus of Hsc70-interacting protein (CHIP) is a Hsp70/Hsp90 co-chaperone and exhibits E3 ubiquitin ligase activity. The high-affinity Hsp90-CHIP complex recognizes and selectively regulates their client proteins. CHIP also works with its own E3 ligase activity independently of Hsp70/Hsp90. Here, we investigated the role of CHIP in regulating EGFR in lung adenocarcinoma and also evaluated the specificity of CHIP's effects on mutant EGFR.In HEK 293T cells transfected with either WT EGFR or EGFR mutants, the overexpression of CHIP selectively decreased the expression of certain EGFR mutants (G719S, L747_E749del A750P and L858R) but not WT EGFR. In a pull-down assay, CHIP selectively interacted with EGFR mutants and simultaneously induced their ubiquitination and proteasomal degradation. The expressions of mutant EGFR in PC9 and H1975 were diminished by CHIP, while the expression of WT EGFR in A549 was nearly not affected. In addition, CHIP overexpression inhibited cell proliferation and xenograft's tumor growth of EGFR mutant cell lines, but not WT EGFR cell lines. EGFR mutant specific ubiquitination by CHIP may provide a crucial regulating mechanism for EGFR in lung adenocarcinoma. Our results suggest that CHIP can be novel therapeutic target for overcoming the EGFR TKI resistance. (C) 2016 Elsevier Inc. All rights reserved.